Variable ratio gearing



DeC. 9, 1947. s RQBSQN I 2,432,210

' VARIABLE RATIO GEARING Filed March 10, 1945' 5 Sheets-Sheet l I nventor v y MEX/M 5/044 1 41.

I Atiorney Dec. 9, 1947. B. s. ROBSON 2,432,210 I VARIABLE RATIO GEARING Filed March 10, 1945 5 sheets-sheet 2 In ventor 5/7'20/7 Ye/by Robson L r I Attorneys Dec. 9, 1947. B. s. ROBSON VARIABLE RATIO GEARING Filed March 10, 1945 5 Sheets-Sheet 5 z W v NJ x M a T a f iiLuvufr l n MM 7 2 wwq/rk/fik ykfi A,

I Inventor v B27700 Se/by Robson Attorneys Dec. 9, 1947. s ROBSON 2,432,210

VARIABLE RATIO GEARING Filed March 10, 1945 5 Sheets-Sheet 4 Inventor Attorneys Dec. 9, 1 947. 5, s, RQBSQN 2,432,210

VARIABLE RATIO GEARING Filed March 10, 1945 5 Sheets-Sheet 5 k k l Inventor Attorneys and with small wear.

Patented Dec. 9, 1947 VARIABLE RATIO GEARING Briton Selby Robson, Huyton Quarry, near Liverpool, England, assignor, by mesne assignments, to British Insulated Callenders Cables Limited, London, England, a company. of Great Britain Application March 10, 1945, Serial.No..-.582 ,1 54

In Great Britain March 24, 1944 7 Claims.

7 This invention relates to variable ratio gearing of thetype in which transmission of motion takes place through a friction disc (hereinafter called the transmitting disc) on the'face of which work input and output discs which make edge contact with it, the ratio being varied by producing'relative' movement between the transmitting discand'the input and output discs so that the distances of these discs from the centre of the transmitting disc are changed progressively. In such a gear the input and output discs have their nominal lines of contact with the transmitting disc on one and the same line, which passes through the axis of rotation of the transmitting disc,"and relative movement between input and output discs and the transmitting disc takes place parallel to this line; In many cases the input and output discs are fixed in'position relative to each other so that they keep the same distance apart while changing their positions relative to the centre'fof the'transmitting disc. V

"The invention provides an improved form of gear of this type in which substantial power may be transmitted in a structure of compact form This is done by utilising a number of sets of transmitting and input and output discs working in parallel and arranged to share theload accurately, even under conditions such that appreciable wear takes place. In this arrangement each set of input and output discs is mounted in a frame or other carrier and these carriers are arranged alternately with the transmitting discs to form a group, the outside members of'which are transmitting discs. The mem bers of the group are mounted under compression acting along the common axis oi the transmitting discs and all, or all but one of them, are capable of movement under this pressure so that uniform contact pressure is maintained between all the adjacent disc surfaces. Accordingly, the power transmitted at each of these surfaces is substantially the same at any instant.

The drives to the input discs are connected in parallel in, such a way that slight lateral displacement of some of the parts relative to the others can take place without disturbing the drive. A similar arrangement is also provided on the output side. All the carriers are operatively grouped together and similarly guided as a set while the transmitting discs are also mounted as a set. These two sets are supported so that relative movement can take place between them. Preferably the carriers are fixed and the transmitting discs are moved so as to vary the relative positions elf-the input and output discs on the transmitting discs.- The inventionwillbedescribed further withthe aid of 'the accompanying drawings wherein:

Fig-ur'e"l is an' underneath planet the gearma ns lower half of the figure being a section on I-I-of Figure 2 and the upper half being a section taken on the line A- -B of Figure 2.

Figureais a s'ectional elevation on the line II-"-II of Figure 3. V V Figure 3 is a sectional elevation 'onthe line III+III Qf Figure'Z. 5 Figure 4 is-anunderneath plan view with certain parts removed;

fFi'gure-5 is a sectional elevation on -V-V- of gures,

Figure 6 is an end elevation of a detail partly in section; the section being taken on the line VI--VI ofFigure 7 and, 3 I Figure? is a side elevation partly in section, of the detail shown in Figure 6. r Figure 8 is aside elevation'of a detail illustrating a'modificationand, "'Figure'9'is a 'sid elevationof another detail.

Referring first of all to Figures 1-7 and'particularly to Figures 1-3, the variable ratio gearing comprises a'set of transmitting discs 8, 9, land. H and sets of discs 12,15, l3, l6,an'dl4,' l'l'. The discs i2 and t5 form a set, the discs l3 and I6 form another set and the'discs l4 and l! form a thirdset. The transmitting discs and the three sets "of discs are arranged to work in parallel. The main shafts to'which power is supplied and from which power is delivered are indicated by the reference numerals l8 and I9. The three discs 12; i3 and M are associated respectively-with th'e'three gearwheelsi52, 51 and 52 and'the three discs I5, l6 and I1 are associated respectively with the gear wheels 59, GI and 59. Power from a prime mover (not shown) may be delivered to the main .shaftIB and be transmitted through the gearing to the main shaft l9 or the power maybe delivered to the shaft i9 and be transmitted through the gearing tothe shaft l8." For conven ience of description it will be assumed that power deliveredfrom a prime mover to shaft [3 is transmitted through'the gearing to the shaft I9, the shaft !8 beingreferred to in'the following descripti'on the main input shaft and the shaft l9 as the main output shaft. Similarly the discs l2, l3 andl4 will be referred to as the input discs and the gear wheels associated therewith, as the input gear wheels, and the'disc's [5, I6 and I1, asthe output discs and the gear wheels associated therewith, as the output gear wheels.

In the example illustrated power delivered to the main input shaft I 8 is delivered through three paths in parallel to the main output shaft I9. In one of these power delivered to input disc I3 is transmitted by discs 9 and If! to output disc I6. In another path, power delivered to input disc I2 is transmitted by discs 8 and 9 to the output disc I and in the third path, power delivered to input disc I4 is transmitted by discs III and I I to th output disc IT. The three input gear wheels 52, 51 and 52 are coupled together and similarly, the three output gear wheels 59, BI and 59 are coupled together.

In the particular arrangement being described, there are two outer sets of input and output discs, the input disc I2 and its output disc I5 forming one set and the input disc I4 and its output disc I1 forming the other outer set. Between these two sets and in symmetrical relationship thereto is mounted the third set consisting of input disc I3 and output disc I6. All of the input and output discs are of the same size and all the input, output and transmitting discs are mounted in compression so as to maintain adjacent working faces in contact. The distance between the input and output discs of each set is the same and remains fixed and the ratio of transmission is varied by moving the transmitting discs 8-II as a whole in a direction at right angles to the common axis of those discs. Adjacent transmitting discs rotate in opposite directions and the input and output discs of a set also rotate in opposite directions.

Each set of input and output discs is mounted in a carrier which will be described later and a portion of which is shown at 65 in section in the upper half of Figure 1 and in an underneath plan view in the lower half of that figure. It will be seen from Figure 1 that the carriers and their sets of input and output discs are arranged alternately with the transmitting discs to form a group and that the outside members of the group are transmitting discs, namely, the discs 8 and 11.

The transmitting discs are all'mounted in ball bearings 29 upon a shaft 2| having its longitudinal axis at right angles to the common axis of the main input and output shafts I8 and I9. The transmitting discs are spaced appropriately along the shaft and the latter is mounted at the lower end of a frame 32, passing through bushes 35 forming part of the frame. The upper part of the frame is of substantially rectangular shape in plan having sides 34 and ends 33 and the upper part is disposed horizontally. The two ends of the frame are provided with end plates or webs I33 which, as will be seen from Figure 2, taper off in width in a downward direction. The bushes 35 are connected to the upper part of the frame 32 by the end plates I33 and also by spaced intermediate webs I34, the two outer bushes being each connected to the frame by one of the end plates I 33 and by an adjacent web I34, the inner bush beingconnected by a pair of webs I34. The latter at their upper ends are connected to the sides 34 of the frame. In cross-section the frame 32 is of triangular shape.

The shaft 2! is axially slidable in the bushes 35 and it has at one end a helical compression spring 30, the pressure of which is adjustable by turning a nut 3I on the end of the shaft. The other end of the shaft passes through a ring 25 and it also passes freely through a hole in a recessed plate 26 which houses an enlarged head 28 integral with the shaft 2I and through which passes a tapering pin 29. The plate 26 and ring 25 are spaced by ball bearings 21, the ring 25 rotating with the transmitting disc II.

As the shaft 2I is slidable'axially, the pressure exerted by the compression spring 30 tends to press the transmitting discs 8 and 9 and the set of input and output discs disposed between those discs in one direction towards the non-slidable set of input and output discs I3, I6 and the spring tends also to press the transmitting discs I0 and I I and the set of input and output discs mounted between those transmitting discs in the opposite direction towards the input and output discs I3, IS. The spring 30 thus tends to press all the discs together. In order that the compression may be effective, to maintain contact at the working surfaces, the transmitting discs have a certain limited amount of movement in a direction parallel with their common axis and the two outer sets of input and output discs, namely the discs I2, I5 and I4, I! are permitted a limited amount of movement in a direction parallel with the longitudinal axis of the shaft 2 I. Axial movement of the transmitting discs 8I I relative to the shaft 2I, which latter does not rotate, is obtained by mounting the inner ball bearing rings I09 in bushes IIlI provided with keys I02 slidable in keyways I93 in the shaft 2|. The amount of sliding movement required for the transmitting and sets of input and output discs, in practice, will be very small.

The shaft 2| at the end at which the compression spring 30 is mounted passes freely through a hole in a recessed plate 23 which serves to locate the thrust bearing 24.

As already described, the set of transmitting discs is mounted in the frame 32 which is fixed as regards movement in a direction parallel with the axis of the shaft 2I but is slidable in a direction at right angles to that axis. The means for effecting this movement is understood most easily by references to Figures 2 and 4. The frame is slidably mounted upon a pair of horizontally disposed parallel rods 36 which are themselves held rigidly in position by passing through pairs of l"gs 38 having holes 31 and fixed to and extending downwards from a plate I, which latter, in the example being described, is the cover of a casing housing the gearing. One of the sides 34 of the upper horizontal part of the rame 32 is engaged by a screw 39 which enters a tapped hole 93 in the side and has a plain stem 40 and a knob 4| for turnin the screw. Axial movement of the screw is prevented by a portion 42 of the knob which portion is disposed between the knob 4| and a cover plate 43 and by a collar 44 fixed to the stem 40 and bearing against a bearing plate I3 integral with the cover I. By turning the knob M the frame 32, shaft 2I and all the transmitting discs 8I I are moved at right angles to the longitudinal axis of the shaft to vary the ratio of transmission of the gearing.

The mounting of the sets of input and output discs will now be described, referring first of all to Figure 1. Each of the discs is keyed to a shaft and all the shafts lie in a horizontal plane and the shafts for the input and output discs of a set have their longitudinal axes in alignment. The upper half of Figure 1 shows the shafts 41 and 58 having keyed respectively thereto the input disc I2 and the output disc I5, the two shafts being in axial alignment. The two discs are mounted adjacent the inner ends of their shafts and sprockets 52 and 59 respectively are mounted ad acent the outer ends of the shafts. Each shaft is mounted in ball bearings 50 held apart by a spacing sleeve 5| through which the shaft passes and a spacing ring 53 is mounted on the shaft between the outer of the ball bearings and the sprocket, the whole being held together in a housing 85 by a nut 58 on the inner end of the shaft and a shoulder :36 at the outer end of the shaft. The mounting of the set of discs i2, I5 is the same as that for the set of discs i l, ll and in each case the set of input and output discs is mounted in a carrier of which the two housings 55 form a part.

lhe construction of the carriers for the two outer sets of input and output discs, which have a limited amount of sliding movement in a direction parallel with the longitudinal axis or" the shaft 1!, will be understood by reference in particular to Figures 2 and3. Each carrier inside view forms approximately a U-shaped member having two sides connected together at their lower ends. Each side member of the carrier'is o osed of a pair of upper side plates 65 and of lower side plates El, the adjaends of the plates being connected to a housing 5. At their upper ends the side plates ifiare cted to a bush E i and the side plates ll at th lower ends are also connected to a bush E l. Each pair of side plates is connected by a web i l land the two supports 85 are connected rigidly together by a plate H35 having downwardly extending wells 63.

As stated above the two carriers for the input and out-pi di-cs ill. 95 and i i, ii are of the same cons on and they are nounted on four horizontally disposed rods 62, serving as guides the er reds passing through upper bushes 2 and the lower rods passing through the lower bushes. The two upper rods 1'52 disposed a short distance below the rods 36 and are at right an les thereto they are supported from the cover 2 by bushes 65 which are fixed in a pair of spaced plates it which extend downwardly rum the cover are integral therewith. The

lper rods pass through the bushes 5s. The -.vo carriers are permitted a small amount of movement on the rods 62 in a direction parallel with the lo git udina-l axis of the shaft 2!.

Thecarrier for the set of input and output discs i3, it is fixed, that is to say, it has no sliding I. iovernent parallel to the axis of the shaft stand the mo-uing of those input and output s is. slightly different from that for the other two sets of discs. The input disc 53 is keyed to a shaft 5:; and a ball bearing 55 is provided adjacent the disc. Th shaft passes through a spacing sleeve separating the ball bearing from theinput gear wheel 5? and shaft 5 3 is integral with the main input shaft 58. A nut 48 is provided at the inner end of the shaft 5 3 and the shaft i8 is mounted in ball bearings '55. The output disc :5 is keyed to a shaft 66 which is integral with the main output shaft 39 and the other constructional details are the same as for the input disc [3.

The construction of the fixed carrier for the input and output discs [3, I6 is shown in Figures 6 and 7 to which reference will now be made. The carrier is indicated generally by the reference numeral H and comprises a double bracket each portion of which has a housing l3, one being for the shaft 54 and the other for the shaft til, the inner surfaces of the housings being recessed at their out-er ends to receive the ball bearings 53. Each of the housings E8 is itself supported from thecover. I by .a pair of the plates ll which lie parallel with each other and extend downwards from the cover I and are at right angles thereto and are integral therewith. The plates 10 are also integral with a bearing plate 73 and project inwards at right angles thereto. Each of the plates 13 has an aperture 14 in which is mounted a ball bearing 15 (Figure l) in which the main input or output shaft H8 or I9 is mounted. Between the inner end of each aperture 74 and the outer ends of the corresponding housing 78, the metal of the plates i6 is cut away to provide spaces Si for the mounting of the input and output sprockets 5'! and El respectively. It will be understood that the two housings are in axial alignment.

From the underside of each of the housings i8 there extends downwardly a thick stem or plate $22 having side pieces or webs l9 and terminating in a bush 8E3, the two bushes 69 and the bushes 8% providing for the passage of the rods 52 which pass through the carriers for the other two sets of input and output discs.

The gearing is shown supported inside a casing indicated generally in Figure 1 by the reference numeral 5. The gearing is supported as a whole from the cover l of the casing which has end walls 2 and 3. side walls 4 and 5 and a bot-. tom 8. The bearing plate 73 has an aperture (see Figure 7) for the passage of the stem 46 of the screw 39 which moves the frame 32.

The two bearing plates 13 are received in apertures '12 in the end walls 2, 3 (see Figure 1) and are held in position by bolts 16 which pass through holes in the plates 33 and enter tapped holes in the bearing plates 13.

As will be seen from Figure l, the input and output sprockets are mounted on their shafts between the ends of the carriers and the end walls 2, 3 of the casing i. It will be necessary for the sprockets to provide for the movements of the use outer sets of input and output wheels inwards towards the inner fixed set while maintaining proper driving connection. This result may be obtained by using gear wheels of various forms and with different means for coupling the wheels together. Figure 3 shows two outer sprockets 52 and the sprocket 51 placed between them, the two outer wheels being driven from the middle wheel by a chain 82, the tension of which is adjustable by an eccentrically mounted sprocket 83, the latter being mounted on a stud 84 which enters a tapped hole 55 (Figure 7) provided in the lower end of plate 92. A nut 86 holds the sprocket in position. The sprockets on the output side are similarly arranged.

In the construction described above the carriers for the two outer sets of input and output discs are slidably mounted. This arrangement, however, need not necessarily be adopted and Figure 8 is intended to indicate an alternative arrangement. In that figure, the numeral 81 represents an approximately U-shaped frame. in the two vertically disposed sides of which, are provided housings Q0, one being for the input disc of one set and the other, for the output disc of that set. At its upper end, apertures 89 are provided in bosses $6 and the frame is pivotally mounted upon one of the rods which support the frame 32 (Figure l.) the rod passing through the two apertures 89 so that the compression spring 39 may press the set of input and output discs against an adjacent transmitting disc. Direct drive may be used in place of a chain. Figure 9 illustrates an example of such a drive, the two outer wheels 9! being placed initially at a distance in respect of the centre wheel slightly greater than their pitch diameter so that they are constantly in mesh.

It will be understood that the invention is not limited to an arrangement of transmitting and input and output discs which provide for the transmission of power through three paths in parallel.

In the construction according to the invention the load to be transmitted is split up into parallel paths thus reducing the wear at the working surfaces and the transmitting and input and output discs are maintained in contact, any wear at those surfaces being taken up by appropriate movements of the discs so thatthe load is shared uniformly.

What I claim as my invention is:

1. Variable ratio gearing comprising a shaft, a set of spaced transmitting discs mounted on the shaft, a frame carrying the shaft, sets of input and output discs, carriers for the sets of input and output discs arranged alternately with the transmitting discs, the said transmitting discs, input and output discs and the carriers forming a group, the outer members of which group are transmitting discs, the sets of input and output discs and transmitting discs being arranged to work in parallel, a spring at one end of the shaft maintaining the members of the group under compression, at most one of the said members being fixed and the remainder being movable under the pressure exerted by the spring, and means for moving the frame to move the transmission discs across the working faces of the input and output discs.

2. Variable ratio gearing comprising a shaft, spaced transmitting discs mounted on the shaft, sets of input and output discs the transmitting discs and the input and output discs being arranged to work in parallel, guides disposed at right angles to the shaft, a frame carrying the shaft and slidably mounted upon the guides, guides disposed parallel with the shaft, carriers for the sets of input and output discs, at most one of the said carriers being fixed and the remainder of said carriers being slidably mounted upon the guides disposed parallel with the shaft, the carriers for the input and output discs being arranged alternately with the transmitting discs to form a group, the outer members of which group are transmitting discs, a spring at one end of the shaft maintaining the members of the group under compression, at most one of said members being fixed and the remainder of said members being movable under the pressure exerted by the spring, and means for moving the frame to move the transmission discs across the working faces of the input and output discs.

3. Variable ratio gearing comprising a shaft, spaced transmitting discs mounted on the shaft, sets of input and output discs, the transmitting discs and the input and output discs being arranged to work in parallel, guides disposed at right angles to the shaft, a frame carrying the shaft and slidably mounted upon the guides, carriers for the sets of input and output discs, at most one of said carriers being fixed and the remainder of said carriers being pivotally mounted upon the guides, the carriers being arranged alternately with the transmitting discs to form a group, the outer members of which are transmitting discs, a spring at one end of the shaft maintaining the members of the group under compression, at most one of said members being fixed and the remainder of said members being movable under the pressure exerted by the spring and means for moving the frame to move the transmission discs across the working faces of the input and output discs.

4. Variable ratio gearing comprising an axially movable shaft, a set of transmitting discs mounted on the shaft, a frame carrying the shaft, an inner set of input and output discs and at least one outer set of input and output discs disposed on each side of the inner set of input and output discs, means for moving the frame to move the transmitting discs across the working faces of the input and output discs, the transmitting discs and the input and output discs being arranged to work in parallel, a fixed carrier for the inner set of input and output discs, carriers for the outer sets of input and output discs movable inwards towards the fixed carrier, the carriers for the sets of input and output discs being arranged alternately with the transmitting discs and forming a group of which the outer members are transmitting discs, a spring at one end of the shaft maintaining the members of the group under compression, interconnected input gearing disposed on the input side of the sets of input and output discs for the input discs and interconnected gearing disposed on the output side of those sets, the said input and output gearing maintaining driving connection and permitting movement of th outer sets of input and output discs inwards towards the inner set.

5. Variable ratio gearing comprising at least two input discs and at least two output discs, each input disc co-operating with an output disc and forming a set, a carrier for each of such sets, and at least three transmitting discs spaced along a common axis, which is substantially at right angles to that of each set of input and output discs, the carriers being arranged alternately with the transmitting discs to form groups having transmitting discs as their outside members, means for producing relative movement between the sets of input and output discs and the transmitting discs to vary the transmission ratio, means acting along the common axis of the transmitting discs for placing the members of a group under compression, at most one of the members of the group being fixed and the remainder of the members being movable under the compression means.

6. Variable ratio gearing comprising at least two input discs and at least two output discs, each input disc co-operating with an output disc and forming a set, a carrier for each of such sets, and at least three transmitting discs spaced along a common axis, which is substantially at right angles to that of each set of input and output discs, the carriers for the input and output discs being arranged alternately with the transmitting discs to form groups having transmitting discs as their outside members, means coupling all the input discs together, means coupling all the output discs together, means for producing relative movement between the sets of input and output discs and the transmission discs to vary the gear ratio, means acting along the common axis of the transmitting discs for placing the members of a group under compression, at most one of the members of the group being fixed and the remainder being movable under the compression means, the coupling means remaining effective whilst permitting such movement to take place.

'7. Variable ratio gearing comprising a shaft, at least three transmitting discs spaced apart along the shaft, at least two input discs and at least two output discs, each input disc co-operating with an output disc and forming a set, the discs of each set having their common axis substantially at right angles to that of the shaft, a carrier for each of such sets, the carriers being arranged alternately with the transmitting discs to form groups of which the outside members are transmitting discs, means acting along the axis of the shaft for placing the members of a group under compression, at most one of the members of the group being fixed and the remainder being movable under the compression means, the movable transmitting discs being axially slidable upon the shaft upon which they are mounted and the movable carriers being pivotally mounted 15 REFERENCES CITED The following references are of record in the 0 file of this patent:

UNITED STATES PATENTS Number Name Date 790,362 Guttner May 23, 1905 1,042,720 Richards Oct, 29, 1912 

